Generator main field connection

ABSTRACT

A main field connection to connect to a main field winding has a semi-cylindrical portion with an axially thicker outer surface, an axially thinner inner surface, with an aperture. An extending portion extends from the semi-cylindrical portion to a remote extending end. The remote extending end extends for a first axial distance. The axially thicker portion of the semi-cylindrical portion extends for a second axial distance. A ratio of the first axial distance to the second axial distance is between 0.65 and 1.4. A rotating assembly, a generator and a method are also disclosed.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.16/528,896 filed Aug. 1, 2019.

BACKGROUND

This application relates to a main field connection for use in a highspeed generator.

Generators are known and typically have an input shaft connected to asource of rotation. The input shaft rotates when driven by the source ofrotation causing a main field winding to rotate adjacent to a mainstator. Electrical energy is generated in the main stator from therotation of the main field winding.

A DC voltage must be supplied to the main field winding. In knowngenerators, an exciter stator is positioned adjacent an exciter rotorand transmits AC three phase current to a rectifier pack. The rectifierpack rectifies the three phase AC current into a DC current. A positivebus and a negative bus extend from the rectifier pack into positive andnegative rails associated with a connector or resistor pack. Theresistor pack communicates the DC voltage through negative and positivemain field connections to the main field windings.

In the past, the main field connections have utilized beryllium copperelements to connect to both positive and negative rails.

SUMMARY

A main field connection to connect to a main field winding has asemi-cylindrical portion with an axially thicker outer surface, anaxially thinner inner surface, with an aperture. An extending portionextends from the semi-cylindrical portion to a remote extending end. Theremote extending end extends for a first axial distance. The axiallythicker portion of the semi-cylindrical portion extends for a secondaxial distance. A ratio of the first axial distance to the second axialdistance is between 0.65 and 1.4.

A rotating assembly, a generator and a method are also disclosed.

These and other features may be best understood from the followingdrawings and specification.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 schematically shows a high speed generator.

FIG. 2 shows a connection detail.

FIG. 3 shows the connection of a connection assembly to a main fieldrotor.

FIG. 4A shows connection details.

FIG. 4B shows a detail of FIG. 4A.

FIG. 4C shows yet another detail.

FIG. 5 shows a prior art connector.

FIG. 6A shows a new connector in a perspective view.

FIG. 6B is a top view of the new connector.

FIG. 6C is a cross-sectional view through the new connector.

DETAILED DESCRIPTION

FIG. 1 shows a high speed generator 20 receiving an input 22. Input 22could be a shaft driven by a turbine in an associated gas turbine engine19 such as used on an aircraft. The input shaft 22 drives a shaft 21.

An exciter stator 25 surrounds an exciter rotor 24. A rectifier assembly26 rotates with the exciter rotor 24 and the shaft 21.

FIG. 2 shows the rectifier pack 26 having connections 30P and 30Nextending toward a connection assembly 32.

Returning to FIG. 1 , the connection assembly 32 includes a positiverail, which receives the connection 30P, and negative rail whichreceives connection 30N.

In practice, three phase AC current is supplied from the exciter stator25 to the exciter rotor 24. That three phase AC current is rectified inDC by the rectifier pack 26 and supplied to the connection assembly.Then, from the connection assembly the positive and negative main fieldconnections are connected to the main field windings 36. Main stator 38is also shown. As mentioned above, during operation, the input 22 causesthe rotating components to rotate and electric power is generated at themain stator 38.

FIG. 3 shows the connection assembly 32 and its connection to the mainfield winding 30. Fasteners 40 and 42 secure main field connections 44.As understood, one of the main field connections 44 provides a positiveconnection and the other provides a negative connection.

FIG. 4A shows further details of the main field connections 44 eachhaving an arm 46 extending to be between a spring 48 received inrespective pockets 17.

FIG. 4B shows the springs 48 having a pair of spring hoops 59, one ofwhich receives a connection pin C. The spring 48 is received in pocket17 and flexes outwardly such that the hoops 59 are biased against arm 46at an inner end 60.

FIG. 4C shows a connection rail 50 having a pin C received in one of thehoops 59. As can be seen, the inner end 60 of the connection 44 extendsfor a greater axial distance than does an outer portion 66 whichreceives the fastener 40 to connect to the field winding 30.

FIG. 5 shows a detail of the prior art connection 44. As shown, anaperture 62 will receive the fastener. A part cylindrical portion whichreceives the pin and includes the aperture 62 includes an axiallythicker outer portion 66 and an inner axially thinner portion 64 thatwill actually support the pin. The arm 46 extends to the inner connectorend 60. As shown, the inner connector end 60 could be called a tang. Abend 61 connects the extending arm 46 into the tang 60. The tang 60could be said to extend for an axial distance d₁. The thicker portion 66could be said to extend for an axial distance d₂. In known connections ad₁ was 0.200 inch (0.508 cm) and d₂ was 0.075 inch (0.191 cm). The bend61 provides a high stress zone. The high stress zone provided by thebend 61 results in the connection 44 being formed of beryllium copper.It would be desirable to utilize a material other than beryllium copper.

FIG. 6A shows a disclosed main field connection 80. Main fieldconnection 80 has a body 81 with the part cylindrical portion 82 with anaxially thicker portion 88 and the axially thinner portion 86. Anaperture 84 extends through the thinner portion 86. The connection 80 isintended to be connected into the same location as the connections 44 inthe prior art. An extending portion 90 extends to a remote end 92.

As can be appreciated in FIG. 6B, remote end 92 has chamfers 94 on eachof two circumferential sides.

FIG. 6C is a cross-section which bisects aperture 84 and remote end 92.As shown, inner or remote end 92 extends for an axial distance d₃. Theextending portion 90 has a first section 93 extending axially away fromthe part cylindrical portion 82 at an angle A, and then to a remoteextending portion 96 which extends in a direction parallel to a plane ofthe part cylindrical portion 82. The thicker portion 88 of the partcylindrical portion 82 extends for an axial distance d₄. The axialdimension is defined through a center point C of aperture 84.

d₃ and d₄ may be 0.070 inch (0.178 cm) (+/−0.010 inch) (0.025centimeters). The thinner portion may extend for an axial distance thatis half of d₄.

In embodiments, it could be said that a ratio of d₃ to d₄ is between0.65 and 1.4. Although defined here as a third and fourth distance, asclaimed, they will be a first and second axial distance.

The angle A may be 22°. In embodiments, the angle A may be between 15and 30°. A distance from center point C and a point E on the end 92 isidentified as d₅. In embodiments, d₅ is 0.960 inch (2.438 centimeters)(+/−0.010 inch) (0.025 centimeters). A ratio of d₅ to d₁ may be between10 and 18.

Connection 80 may be stamped of a copper which is of a lower strengthand less challenging than beryllium copper. The connection 80 is stampedfrom a thin strip of copper. The axially thinner portion 86 may becoined into the stamped semi-cylindrical portion 82.

A method of replacing a connection in a generator comprising removing aremoved connection between a connection assembly 32 and a main fieldwinding 30 and replacing the removed connection with a replacementconnection 80. The replacement connection is connected to a main fieldwinding. The replacement connection 80 has a semi-cylindrical portion 82with an axially thicker outer surface 88, an axially thinner innersurface 86 with an aperture 84. An extending portion 90 extending fromthe semi-cylindrical portion 82 to a range end 92. The extending endextending for a first axial distance d₁ and the axially thicker portionof the semi-cylindrical portion extending for a second axial distanced₂. A ratio of the first axial distance to the second axial distance isbetween 0.65 and 1.4.

In embodiments, the removed connection is removed as part of the entirerotating assembly. In another embodiment, the removed connection isremoved on its own and replaced with the replacement connection.

Although an embodiment of this invention has been disclosed, a worker ofordinary skill in this art would recognize that certain modificationswould come within the scope of this disclosure. For that reason, thefollowing claims should be studied to determine the true scope andcontent of this disclosure.

The invention claimed is:
 1. A method of replacing a connection in agenerator comprising: removing a removed connection between a connectionassembly and a main field winding and replacing said removed connectionwith a replacement connection, said replacement connection connected tothe main field winding; the replacement connection having asemi-cylindrical portion with an axially thicker outer surface, anaxially thinner inner surface and with an aperture, and an extendingportion extending from said semi-cylindrical portion to a remote end;and an axial dimension defined through a center point of said aperture,said remote end extending for a first axial distance and said axiallythicker portion of said semi-cylindrical portion extending for a secondaxial distance with a ratio of said first axial distance to said secondaxial distance being between 0.65 and 1.4.
 2. The method of replacing aconnection as set forth in claim 1, wherein said first and second axialdistances are equal within a margin of error of +/−0.010 inch.
 3. Themethod of replacing a connection as set forth in claim 2, wherein athird distance is defined from said center point of said aperture tosaid remote end, and a ratio of said third distance to said first axialdistance is between 10 and
 18. 4. The method of replacing a connectionas set forth in claim 3, wherein said first axial distance and saidsecond axial distance are each 0.070 inch (+/−0.010 inch).
 5. The methodof replacing a connection as set forth in claim 4, wherein saidreplacement connection is replaced between the same connection assemblyand main field windings that had previously been connected by saidremoved connector.
 6. The method of replacing a connection as set forthin claim 4, wherein said replacement connection is replaced into saidgenerator with an entire replaced assembly including a main fieldwinding and connection assembly.
 7. The method of replacing a connectionas set forth in claim 1, wherein said replacement connection is replacedbetween the same connection assembly and main field windings that hadpreviously been connected by said removed connector.
 8. The method ofreplacing a connection as set forth in claim 7, wherein said first andsecond axial distances are equal within a margin of error of +/−0.010inch.
 9. The method of replacing a connection as set forth in claim 7,wherein a third distance is defined from said center point of saidaperture to said remote end, and a ratio of said third distance to saidfirst axial distance is between 10 and
 18. 10. The method of replacing aconnection as set forth in claim 1, wherein said replacement connectionis replaced into said generator with an entire replaced assemblyincluding a main field winding and connection assembly.
 11. The methodof replacing a connection as set forth in claim 10, wherein said firstand second axial distances are equal within a margin of error of+/−0.010 inch.
 12. The method of replacing a connection as set forth inclaim 10, wherein a third distance is defined from said center point ofsaid aperture to said remote end, and a ratio of said third distance tosaid first axial distance is between 10 and
 18. 13. The method ofreplacing a connection as set forth in claim 1, wherein a third distanceis defined from said center point of said aperture to said remote end,and a ratio of said third distance to said first axial distance isbetween 10 and
 18. 14. The method of replacing a connection as set forthin claim 13, wherein said first axial distance and said second axialdistance are each 0.070 inch (+/−0.010 inch).
 15. The method ofreplacing a connection as set forth in claim 1, wherein said first axialdistance and said second axial distance are each 0.070 inch (+/−0.010inch).
 16. The method of replacing a connection as set forth in claim 1,wherein there is a positive connection and a negative connection betweenthe connection assembly and the main field winding, and one of thenegative and positive connections being said removed connection.
 17. Themethod of replacing a connection as set forth in claim 16, wherein saidconnection assembly includes a positive rail and a negative rail. 18.The method of replacing a connection as set forth in claim 17, wherein afastener secures said replacement connection.
 19. The method ofreplacing a connection as set forth in claim 1, wherein a fastenersecures said replacement connection.
 20. The method of replacing aconnection as set forth in claim 1, wherein said replacement connectionis stamped out of a copper material.